The Research About Classification Of ASIC Curr-ents And Distribution Of ASIC Subunits In Rat Dorsal Root Ganalion Neurons

Objective:(1) To verify the classification of characteristics proton-gated currents in rat dorsal root ganglion neurons.(2) To observe the expression and distribution of four kinds ASIC subunits in dorsal root ganglion neurons ; To presume the correlation between ASIC subunits and electrophysiological characteristics of single acute isolated DRG neurons.Methods:Recording proton-gated currents from neurons freshly dissociated from rat DRG by whole-cell patch technique.Use immunohistochemical ABC staining to observe expression and distribution of ASIC subunits, and use high-definition graphic analysis system (HPIAS) to accomplish images Acquisition and analyze them.Results:I Proton-gated currents mediated by ASICs are classified into four types based on the characteristics of their activation and desensitization, shape of current, cell size and dependence of pH value. I recorded them, they are T-Type (Transient inward current), S-Type (Sustained inward current),B-Type (Biphasic inward current) and O-Type (Opposite current). The proportions of these four types currents are S-Type(64.5%)> O- Type(20.3%)> B- Type(9%)> T- Type (3.8%).ⅡThe results of immunohistochemistry shows the numbers of ASIC-receptor subunits im- munoreactive in DRG histological sections: ASIC3(79.50±23.83)> ASIC4(61.00±25.97) > ASIC2(55.25±13.12)>ASIC1(42.00±6.92).The numbers of ASIC1 and ASIC3 exist extraordinary disparation(P<0.01),and the numbers of ASIC2和ASIC3 exist noticeable disparation(P<0.05).ⅢImmunohistochemistry results showed that ASIC1, ASIC3 immunoreactivity DRG neurons mainly concentrate in the middle (25μm30μm) DRG neurons ( p<0.05 ) . ASIC2 immunoreactivity DRG neurons mainly are middle and large size Cells; ASIC4 immunoreactive neurons mainly are middle size cells(p<0.05).Conclusion:I Proton-gated currents recorded from acute isolated rat DRG neurons are classified into four types:T-type ,B-type ,O-type ,S-type. There are some differences among the proportions of four types currents.ⅡThe numbers DRG neurons which express ASIC1, ASIC2, ASIC3, ASIC4 subunits are different. Besides, the four receptor subunits distribute differently in different size DRG neurons.